A-level Physics (Advancing Physics)/Diffraction/Worked Solutions

1. What is the width of the central bright fringe on a screen placed 5m from a single slit, where the slit is 0.01m wide and the wavelength is 500 nm?

$\frac{W}{L}\approx \frac{\lambda }{d}$

$\frac{W}{5}\approx \frac{500\times 10^{-9}}{0.01}$

W = 250μm, but since this is only half the beam, the beam is 500μm wide.